Five years of using cocoa black ants, to control cocoa pod borer at farmer plot – an epilogue

Cocoa Black Ants (CBA), Dolichoderus thoracicus (Smith) was introduced as a biological control agent against Cocoa Pod Borer (CPB), Conopomorpha cramerella (Snellen) at a farmer's plot from Mac 2003 to November 2008. The study plot which is 0.4 hectare is situated at Lekir, Perak had matured cocoa trees with coconut as a shade tree. The plot harbored very low CBA at the beginning of the study. Introduction of artificial ant nests stuffed with dried cocoa leaves was conducted to enhance the CBA population. Mealy bugs, Cataenococcus hispidus that have close mutualistic association with CBA was also introduced by putting 2" x 3" mealy bug chips especially on the cocoa cherelles within the trees or next to the cocoa flowers. In the first data collection on May 2003, the Average Damage Severity Index (ADSI) value in the plot is high (3.0061) which indicated Medium to Heavy pod borer infestation. The percentage of good pods was very low which 35.582% is. A year after the first augmentation which is on May 2004, the ADSI value was 2.57 and the percentage of good pods was 53.98 The ADSI value and percentage by May 2005 declined to 2.36 and 53.33. However in May 2006, ADSI value increased to 2.848 and this also led to a lower percentage of good pods (49.71). The drought period from January to April 2006 may have contributed to the increased of the ADSI value. After extensive nests augmentation with replacements throughout year 2006, the ADSI values decreased to 1.81 and the plot fall into the categorized Slight to Light Infested Plot in May 2007. After five years from the first augmentation of CBA in May 2008, it is found that the ADSI value is gradually reduced to 1.33 and the plot still considered as Slight to Light Infested Plot. The percentage of good pods were consistent with more than 75% of good pods obtained at each sampling occasions from September 2006 until November 2008. Low percentages of CPB infestation and ADSI values proven on the efficacy of CBA as a biological control agent, and can reduce CPB infestation throughout time.